System.out.println("欢迎使用抽奖富翁系统");
System.out.println("\t1.注册");
System.out.println("\t2.登录");
System.out.println("\t3.抽奖");
System.out.println("***");
Scanner in = new Scanner(System.in);
System.out.print("请选择菜单：");
int sc = in.nextInt();
switch (sc) {
case 1:
System.out.println("抽奖富翁系统----->注册");
break;
case 2:
System.out.println("抽奖富翁系统----->登录");
break;
case 3:
System.out.println("抽奖富翁系统----->抽奖");
break;
default:
System.out.println("输入错误，请重新输入：");
break;
}
public static void main(String[] args) {
System.out.println("欢迎使用抽奖富翁系统");
System.out.println("\t1.注册");
System.out.println("\t2.登录");
System.out.println("\t3.抽奖");
System.out.println("***");
Scanner in = new Scanner(System.in);
String answer="";
do {
System.out.print("请选择菜单：");
int sc = in.nextInt();
switch (sc) {
case 1:
System.out.println("抽奖富翁系统----->注册");
System.out.println("是否选择继续:Y/N");
answer=in.next();
continue;
case 2:
System.out.println("抽奖富翁系统----->登录");
System.out.println("是否选择继续:Y/N");
answer=in.next();
continue;
case 3:
System.out.println("抽奖富翁系统----->抽奖");
System.out.println("是否选择继续:Y/N");
answer=in.next();
continue;
default:
System.out.println("输入错误，请重新输入：");
break;
}
} while ( answer.equals("Y"));
System.out.println("程序结束，退出程序。");
}
System.out.println("欢迎使用抽奖富翁系统");
System.out.println("\t1.注册");
System.out.println("\t2.登录");
System.out.println("\t3.抽奖");
System.out.println("***");
Scanner in = new Scanner(System.in);
String answer="";
do {
System.out.print("请选择菜单：");
int sc = in.nextInt();
switch (sc) {
case 1:
System.out.println("抽奖富翁系统----->注册");
System.out.println("输入用户名:");
String name=in.next();
System.out.println("输入密码:");
int password=in.nextInt();
int card= (int)(Math.random()*9000+1000);
System.out.println("card:"+card);
System.out.println("注册成功，请记住你的会员卡号，会员名，密码");
System.out.println("会员卡号\t"+"会员名\t"+"密码");
System.out.println(card+"\t"+name+"\t"+password);
System.out.println("是否选择继续:Y/N");
answer=in.next();
continue;
case 2:
System.out.println("抽奖富翁系统----->登录");
System.out.println("是否选择继续:Y/N");
answer=in.next();
continue;
case 3:
System.out.println("抽奖富翁系统----->抽奖");
System.out.println("是否选择继续:Y/N");
answer=in.next();
continue;
default:
System.out.println("输入错误，请重新输入：");
break;
}
} while ( answer.equals("Y"));
System.out.println("程序结束，退出程序。");
-----------------
System.out.println("欢迎使用抽奖富翁系统");
System.out.println("\t1.注册");
System.out.println("\t2.登录");
System.out.println("\t3.抽奖");
System.out.println("***");
Scanner in = new Scanner(System.in);
String answer = "";
int password = 0;
String name = "";
int card = 0;
do {
System.out.print("请选择菜单：");
int sc = in.nextInt();
switch (sc) {
case 1:
System.out.println("抽奖富翁系统----->注册");
System.out.println("输入用户名:");
name = in.next();
System.out.println("输入密码:");
password = in.nextInt();
card = (int) (Math.random() * 9000 + 1000);
System.out.println("card:" + card);
System.out.println("注册成功，请记住你的会员卡号，会员名，密码");
System.out.println("会员卡号\t" + "会员名\t" + "密码");
System.out.println(card + "\t" + name + "\t" + password);
System.out.println("是否选择继续:Y/N");
answer = in.next();
continue;
case 2:
System.out.println("抽奖富翁系统----->登录");
for (int i = 0; i < 3; i++) {
System.out.println("请输入你的会员卡号");
int card1 = in.nextInt();
System.out.println("请输入你的会员会员名");
String name1 = in.next();
System.out.println("请输入你的会员名密码");
int password1 = in.nextInt();
if (card1 == card && name1.equals(name) && password1 == password) {
System.out.println("登录成功");
break;
}
if (card1 != card || !name1.equals(name) || password1 != password) {
System.err.println("输入错误，请重新输入，你还有：" + (2 - i) + "次机会");
continue;
}
}
System.out.println("是否选择继续:Y/N");
answer = in.next();
continue;
case 3:
System.out.println("抽奖富翁系统----->抽奖");
System.out.println("是否选择继续:Y/N");
answer = in.next();
continue;
default:
System.out.println("输入错误，请重新输入：");
break;
}
} while (answer.equals("Y"));
System.out.println("程序结束，退出程序。");
}
System.out.println("欢迎使用抽奖富翁系统");
System.out.println("\t1.注册");
System.out.println("\t2.登录");
System.out.println("\t3.抽奖");
System.out.println("***");
Scanner in = new Scanner(System.in);
String answer = "";
int password = 0;
String name = "";
int card = 0;
do {
System.out.print("请选择菜单：");
int sc = in.nextInt();
switch (sc) {
case 1:
System.out.println("抽奖富翁系统----->注册");
System.out.println("输入用户名:");
name = in.next();
System.out.println("输入密码:");
password = in.nextInt();
card = (int) (Math.random() * 9000 + 1000);
System.out.println("card:" + card);
System.out.println("注册成功，请记住你的会员卡号，会员名，密码");
System.out.println("会员卡号\t" + "会员名\t" + "密码");
System.out.println(card + "\t" + name + "\t" + password);
System.out.println("是否选择继续:Y/N");
answer = in.next();
continue;
case 2:
System.out.println("抽奖富翁系统----->登录");
for (int i = 0; i < 3; i++) {
System.out.println("请输入你的会员卡号");
int card1 = in.nextInt();
System.out.println("请输入你的会员会员名");
String name1 = in.next();
System.out.println("请输入你的会员名密码");
int password1 = in.nextInt();
if (card1 == card && name1.equals(name) && password1 == password) {
System.out.println("登录成功");
break;
}
if (card1 != card || !name1.equals(name) || password1 != password) {
System.err.println("输入错误，请重新输入，你还有：" + (2 - i) + "次机会");
continue;
}
}
System.out.println("是否选择继续:Y/N");
answer = in.next();
continue;
case 3:
System.out.println("抽奖富翁系统----->抽奖");
for (int k = 0; k < 4; k++) {
int q=(int)(Math.random()*9000+1000);
System.out.println("本期的幸运数组是："+q);
if (q==card) {
System.out.println("恭喜你是幸运客户，");
break;
}
else{
System.out.println("你不是幸运客户，");
continue;
}
}
System.out.println("是否选择继续:Y/N");
answer = in.next();
continue;
default:
System.out.println("输入错误，请重新输入：");
break;
}
} while (answer.equals("Y"));
System.out.println("程序结束，退出程序。");到了这里本该结束的，但是有一个bug。抽奖功能的实现的一个前提是登陆成功，登录的前提是注册成功。不然直接选择菜单3.而没有经过1和2.就无法抽奖。弄了一个下午，代码大修，才算修改完善。
但是里面还有很多重复，System.out.println("是否选择继续:Y/N");
answer = in.next();
if (answer.equals("Y")) {
continue;
}
else {
System.out.println("程序结束，退出程序。");
return;
这是一个问题。
break；continue；return。用的总是感觉不对。这是第二个问题。
第三个问题。while（true）无线循环。外面无法再写入代码？这个是个问题吗？要是不是的话？岂不是复杂代码无法应用无限循环了。
希望大家能帮我解惑，谢谢。
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